Switching and tunning of the topological edge states from two-dimensional photonic crystal with liquid crystal medium

In order to achieve switching effect of topological edge states, we construct a two-dimensional triangular lattice in which the scatterers are silicon cyclic rings filled of Phenylacetylene liquid crystal (LC). By changing the applied voltage on the liquid crystal, the refraction index of the LC material can be transformed from normal to abnormal ones. The excitation of the topological edge states can be either switched on or switched off dependent on the LC deflection angles under the voltage modulation. Furthermore, the contrast of the field amplitudes in the two opposite direction of the source can be quantitatively tuned. At the same time, the locked transmission direction and robust property of topological edge states is demonstrated. • A two-dimensional photonic crystal (PC) with the liquid crystal rods is designed. • The switching and tuning effect of the topological edge state are achieved. • The robust property of the topological edge states are demonstrated.